1. Technical Field
The present invention relates to an exhaust gas denitrifying system having a noise-reduction structure, and, more particularly, to an exhaust gas denitrifying system having a noise-reduction structure, including a reactor in which a chemical reaction of converting nitrogen oxides included in exhaust gas into nitrogen by nitrifying the nitrogen oxides using a catalyst takes place.
2. Description of the Related Art
The exhaust gas discharged from engines for thermoelectric power plants, ships and the like that use fossil fuels as energy sources includes a large amount of nitrogen oxides (NOx). Nitrogen oxides are known to cause acid rain and respiratory disease. Therefore, various technologies for removing nitrogen oxides from exhaust gas have been developed. Further, when noises generated by the operation of engines and by the flow of exhaust gas are directly discharged to the external environment together with the exhaust gas, they destroy the external environment and become a target for public grievance. Therefore, technologies for reducing these noises have been developed.
FIG. 1 is a block diagram of a conventional exhaust gas denitrifying system using selective catalytic reduction (SCR), including a silencer for reducing noise. Referring to FIG. 1, in the conventional exhaust gas denitrifying system, exhaust gas discharged from an engine passes through a silencer 11 to reduce noise, and is then introduced into a mixing chamber 12 to be mixed with a reductant supplied by a reductant supply unit 13, and then the exhaust gas mixed with the reductant is introduced into a reactor 14 to be denitrified by a catalyst, thereby removing nitrogen oxides from the exhaust gas.
However, since the noises generated by the operation of the engine and by the flow of exhaust gas are reduced only by the silencer 11, it is required to make a large silencer 11 in order to improve the noise-reducing effect. Therefore, there is a problem in that the exhaust gas denitrifying system must be large-sized as well.
Meanwhile, the denitrification of exhaust gas by a catalyst is easily conducted at a high temperature of about 400° C. and high pressure. However, in the conventional exhaust gas denitrifying system, since the exhaust gas which has had its noise reduced by the silencer 11 sequentially passes through the mixing chamber 12 and the reactor 14 to be denitrified, and, as a result, the exhaust gas, temperature and pressure thereof are decreased by the silencer 11 before the gas is denitrified. Therefore, there is a problem in that the denitrification efficiency thereof is lowered.
Further, since the pressure of exhaust gas drops greatly while passing through the silencer 11, the output of an engine must be increased in order to easily discharge the exhaust gas. Therefore, there is a problem in that the consumption of fuel increases, and the efficiency of the engine decreases.